The purpose of this study was 1) to determine if nitric oxide (NO) production measured by serum nitrate and nitrite concentrations and 24 hour urinary nitrate excretion will be higher in patients with rheumatoid arthritis (RA) than healthy controls and 2) to determine if clinical and laboratory parameters of disease activity in RA correlate with levels of NO production. This study was a cross-sectional analysis of NO production in 25 patients with rheumatoid arthritis and 20 healthy controls. Participants were admitted to the Clinical Research Unit and fed a low nitrate and nitrite diet for 72 hours. During the hospitalization blood and urine samples, saliva test, and disease activity assessments were obtained. A total of 45 patients have completed the study (20 healthy controls and 25 patients with rheumatoid arthritis). Analysis of this study is pending. Preliminary results indicate that peripheral blood cells from patients with rheumatoid arthritis are activated for enhanced NO production.